In our domain, precision is the ratio between the number of relevant technologies recovered and the total number of technologies recovered. The closer the precision value is to 1, the greater the number of relevant technologies recovered with ST-Retrieval.Recall is the ratio between the number of relevant technologies recovered and the total relevant technologies known. A recall of 1 indicates that all relevant technologies have been recovered. In addition, MAP [1]} measures, for a set of queries, the average precision for each query. MAP values close to 1 mean that the relevant technologies are within the top-ranked positions. At last, DCG [2]} measures the quality of rankings, in terms of the utility (gain) of a result based on its relevance and position in the ranking. DCG can be divided by the maximum value taken from among all the queries, and then, the values for each query can be averaged to measure the average quality of the rankings. This variant of DCG is called Normalized DCG (nDCG).
